Physics All-Stars

Noted physicist Abraham Pais, biographer of Niels Bohr and Albert Einstein, has sparingly but painstakingly painted here 16 thumbnail portraits of 17 figures of 20th-century physics (with Tsung Dao Lee and Chen Ning Yang portrayed together). Some are unquestionably giants of humanity. These 17 men have in common not only intellectual grandeur but also the author's genuine affection for them. These portraits are thumbnails in length only.

The days of the old-quantum-theory Bohr atom seem remote—a time when the meaning of electron orbitals was contentious—whereas today's world is unquestionably a quantum one. And yet these portraits are not icons from some ancient triptych but have been painted by someone who is our contemporary as well as theirs. Pais is a bridge—a physicist not only of two continents (his autobiography is titled A Tale of Two Continents: A Physicist's Life in a Turbulent World) but also of two worlds, separated in time as well as space. World War II tore asunder the world in which he and most of the characters of this drama grew up. Many regrouped, intellectually and emotionally, on this side of the Atlantic, in many cases at the Institute for Advanced Study at Princeton.

The author's selection of subjects does not presume to be representative. Clearly, there are a few figures generally considered to be among the great physicists of the century whom Pais has chosen not to include—perhaps because they are still alive, or he did not know them well enough, or for other reasons. And yet the figures he does include, all of them men and almost all Europeans, have defined the century in many ways. Some are great personages of physics who may be less familiar to the reading public than the Nobel laureates who are included. Incidentally, Robert Oppenheimer, who figures prominently in A Tale of Two Continents, is not separately portrayed in this volume, but the interactions of the others with Oppenheimer, and their reactions to his fate, form a leitmotiv of The Genius of Science.

Pais's portrayals are insightful, often humorous and always humane. This was a group of intellectual giants, who belonged to a generation of broadly educated and interested scientists, intently focused on the implications for humanity of their work. And although one can point to other epochs of flourishing science and creativity, Pais characterizes the period from 1900 to 1926 as "the most protracted revolutionary period in modern science."

During World War II, a period to which Pais refers understatedly as the "dark days," Pais, like the Frank family, went into hiding in a house in Amsterdam. Hendrik Anthony Kramers, who was his mentor, visited him there once a week, and during one of these visits (as recounted in the chapter on Kramers), the Gestapo raided the house and Pais hid in the attic behind a wall, with Kramers fronting. Pais was caught by the Gestapo in March 1945 and imprisoned, presumably slated for deportation and death. Kramers, known to the world for his work on electromagnetic dispersion relations, wrote to Werner Heisenberg on Pais's behalf, and Heisenberg said he could do nothing. But a copy of the letter from Kramers was conveyed to a high Nazi official by Pais's friend, Tineke Buchter, and ultimately saved his life. In 1946, at age 28, Pais came to study with Bohr and then embarked on a creative career at the Institute for Advanced Study.

Vignettes scattered throughout the book leave the impression that the great Bohr peaked early and had increasing difficulty communicating new ideas with the same lucidity with which he conceptualized them. He appears to have been hard on his protégés: Kramers, according to his wife, got sick and had to be hospitalized after becoming exhausted and depressed by a series of arguments with Bohr over whether energy and momentum are conserved when light is scattered by electrons. An awful lot of physics, we learn, boils down to personality. Bohr and Heisenberg represented, in their day, one level of hard-nosedness, whereas Kramers and Oscar Klein were less assertive. Pais speculates in an understated way that this might, at times, have something to do with who receives Nobel prizes and might explain why some people he feels were deserving were overlooked.

We also learn how much effort may go into a theory before its abandonment. Kramers and Bohr struggled for six years to solve the problem of the nonionized helium spectrum by applying classical mechanics to the electrons. Two hundred pages of Bohr's unpublished notes on this are in the Niels Bohr Archives—quite an outtake!

We learn of Paul Dirac's profound dissatisfaction with the mass and charge infinities of quantum electrodynamics. And we learn that Wolfgang Pauli, as a matter of personality, grasped—and grasped for—very broad overarching principles but had some problems getting along with colleagues in the last few years of his life.

Many of these vignettes are the fruit of a diary Pais meticulously kept over the course of a career and also of some interesting research that included not only the writings of the subjects but, for example, Federal Bureau of Investigation files on Dirac and available data on Nobel prize nominations. Pais clearly makes judicious use of what he knows.

These giants of physics live on in the memories of those who, like Pais, knew them. This biographical collection serves as an excellent introduction for the rest of us.—Samuel J. Petuchowski, Bromberg & Sunstein LLP, Boston